The Physicochemical State of the Proteins in Cow’s Milk.*

Herman Helmholz had his pupil Zahnz construct a filter out of a porous porcelain cylinder, and this form of apparatus was also used by Kehrer.3 Hermann modified Zahn’s method and used powdered porous plate to adsorb the casein. Tiemann, however, several years later made extensive use of a method devised by Lehmann,c in which the milk was placed upon a slightly concave, porous plate, whose surface had been polished with agate. After standing for 14 to 2 hours, the unadsorbed part, consisting of casein and fat, was scraped off and weighed. Tiemann applied this method especially to the study of the proteins of colostrum milk. Camerer and Soldner,T however, have criticized Tiemann’s method of analysis on the ground of the probable lack of uniformity of clay filters and also because they do not regard the casein to be completely retained on the porous plate.